Quick drying lewis-acid and basic polymer modified polyolefin yarn



April 21, 1970 -J. N. GRAY E AL 3,507,607

QUICK DRYING LEWIS-ACID AND BASIC POLYMER MODIFIED FOLYOLEFIN YARN Filed May 2, 1967 AME/EN 7' zs J95 .21'2

TE/VPERA fl/Rf "F INVENTORS (/4 CK /V. GRA Y FOEEAT J. CZA/PKJO/V ROBERT /7/[ L67? ATTORNEY United States Patent O 3,507,607 QUICK DRYING LEWIS-ACID AND BASIC POLY- MER MODIFIED POLYOLEFIN YARN Jack N. Gray, Columbia, Robert J. Clarkson, Winnsboro,

and Robert Miller, Columbia, S.C., assignors to Uniroyal, Inc., New York, N.Y., a corporation of New Jersey Filed May 2, 1967, Ser. No. 635,453 Int. Cl. D06m 11/02 US. Cl. 8--100 6 Claims ABSTRACT OF THE DISCLOSURE Regression in the dyeability of modified polyolefin fiber which has been activated with a Lewis acid or Lewis acid generating material may be prevented by controlled drying of the fiber after activation. For uniformity in dyeability, the time and temperature of drying must be maintained within the critical limits found at or below curve A in FIG. 1.

This invention is directed to a method of preventing the regression in dyeability of polyolefin fibers which contain a nitrogen-containing dye receptor and dyeing adjuvants which are capable of being partially removed by solubilization in water.

BACKGROUND OF THE INVENTION This invention is an improvement on the invention claimed in United Stated Patent 3,315,014, issued Apr. 18, 1967.

It is known that polyolefin yarn may be made more susceptible to dyeing by activation with a number of dyeing adjuvants.

The present invention is directed to polyolefin fibers containing ingredients which may be activated, or made more dye receptive by treatment with a reactant, such as a Lewis acid. The activated fibers may be prepared, for example, in accordance with the process described in application Ser. No. 375,328, filed June 15, 1964, and are characterized by the use of between about 0.5% and 10% of a thermoplastic nitrogen-containing basic dye receptor, such as atactic polyvinyl pyridine, blended with a monoalphaolefin polymer. About 3% of atactic polyvinyl pyridine was used in preparing the blends used inthe following experiments. Activation may be carried out by placing moist yarns in a sulfur dioxide atmosphere for a predetermined time at ambient temperatures.

The invention will be described chiefly with regard to melt-spun, sulfur dioxide-activated fibcrs,of polyolefins, but it is to be understood that it appl es as well to other polyolefin forms activated by other compounds and compositions, which are themselves soluble in water or react with the fiber ingredients to form water soluble compounds, in those instances in which the resulting products suffer from regression in dyeability.

A major problem has been that activated polyolefin yarn has not been uniform in dyeability. The variability was especially apparent where activated, continuous filament yarn was woven, tufted or otherwise formed into a carpet and dyed. Often a streaked carpet resulted, even after a preselection of yarns of matched dyeability was made; and such preselection is time-consuming and expensive.

It has been found that the handling and treatment of polyolefin yarns after activation may adversely afliect dyeability. The lessening of dyeability is termed regression.

It was observed, for instance, that activated polyolefin yarn left in the presence of water for any significant period of time, e.g., 4 to 72 hours, loses to varying extents the ability to be dyed. It was observed that activated Patented Apr. 21, 1970 polyolefin yarn, that was wound onto small (up to onehalf pound) packages and stored on an open rack, consistently dyed uniformly. It was observed that the inner portion of large packages (one-half'to five pounds), that were wound wet, appeared markedly streaked, lighter than expected from the dyeing procedure (sometimes by 20-40%), and otherwise exhibited regression, upon dyemg.

Another observation was that yarn that had been incorporated into a carpet within 4 hours after being activated did not regress. That is, the carpet could be dyed immediately, or weeks later, and dyeing would consistently produce a uniform color of controllable depth. Absence of regression in carpet form was in direct contrast to re gression present in packages of yarn similar to those from which the carpet was made.

Thus, it was found, where the moisture content was maintained at above about 3% OWF for too long a time and/or at too high a temperature, that regression and non-uniform dyeability resulted.

BRIEF DESCRIPTION OF THE DRAWING The figure is a plot of the time between activation and drying against the temperature at which the yarn is maintained. Curve A indicates the preferred limits of time and temperature within which drying must be completed in order to avoid regression. That is, points below curve A are desirable time-temperature combinations, and points above curve A should be avoided.

SUMMARY OF THE INVENTION 'It has been found that regression may be prevented by drying the yarn within a critical period after activation to a low moisture content. Actually, both the length of the period before drying and the temperature at which the yarn is maintained prior to drying have been found to be critical in preventing regression. Wet yarns stored for about six hours or more regressed regardless of the storage temperature. Wet yarns stored for about four hours at ambient temperatures up to F. did not regress beyond a commercially acceptable extent. Wet yarns stored for about one hour at F. did not regress beyond a commercially acceptable extent. Wet yarns maintained for significantly longer than one minute at temperatures of about F. to 212 F, before drying did regress beyond a commercially acceptable extent. The relationship is shown graphically in FIGURE 1.

As described above, curve A of the figure defines the limit of the preferred ranges of time and temperature at which the yarn is maintained prior to drying. The combinations of time and temperature under curve A are preferred. Regression increases, and dyeability becomes poorer, as the distance above the curve increases.

To avoid commercially unacceptable regression, the yarn must be dried to less than 3% water on the weight of the fiber (3% OWF). Preferably the yarn is dried to less than 2% OWF. The normal moisture regain, from 0% moisture content, for sulfur dioxide-activated polyolefin fiber is approximately 0.6% OWF at 65% relative humidity. The preferred moisture content for the yarn is between about 0.6 and 2% OWF at 65% relative humidity.

Drying may be carried out either by using a high air How and relatively low temperatures, for instance ambient temperatures of 60-80 F., or by using low air flow and high temperatures. Maximum drying temperatures depend on the dyeing adjuvant used with the polyolefin. The maximum drying temperature is just below the decomposition temperature of the particular dyeing adjuvant employed, otherwise the yarn may start to discolor. Sulfur dioxide-activated polyolefin fiber should not be heated above about 250 to 260 F.

It has been found that, when drying is conducted at above about 255 F., '"th"e' dyeability actually decreases with increasing temperatures. This phenomenon is not related to regression but appears to be due to a closing off of some of the dye sites, possibly due to partial melting of some of the spherulites present. The preferred maximum drying temperature is about 255 F.

The maximum moisture that yarn can hold prior to drying is a function of the yarn texturization and may be as highas 300% OWF. Texturized yarns retain substantially more water than untexturized yarns, which usually do not hold much over 100% OWF. In the case of sulfur dioxide-activated polyolefin fibers, the minimum amount of water needed during the activation of the yarn to achieve uniform activation to the depth desired is about 9 to 10% OWF. Usually the average moisture levels run higher,about 120% OWF for texturized yarn, in order to assure a uniform distribution of a minimum amount of water in any section of the yarn. However, any amount of water on the yarn in excess of about 3% OWF will cause regression if not removed within the prescribe time period.

' It has been found to be critical to uniformity of dyeability of large amounts of fiber that the time and temperature of drying and storage be substantially similar from batch to batch. Thousands of packages of yarn may be used in making carpets and all of the packages must be dried under substantially the same conditions to obtain maximum uniformity. For example, where one package is dried in about minutes and another package of the same yarn is dried in about two hours, there will be some difference in regression between them although they are both dried to the same moisture content.

Any suitable technique may be used for removing water from the yarn including the following. Drying may be carried out continuously or batch-wise. Air at high velocity, centrifugation, etc., may be used to mechanically remove most of the water as a liquid with the remainder being evaporated off. A high temperature air flow may be used to evaporate the water. Any heating source, including infra red devices, laser beams or any other such device, may be used. Dielectric heating may be used to dry the yarn very rapidly by employing the water as the conducting medium so that once the water is removed the current ceases to flow through the yarn. A yarn that is loose, forinstance, through having been permitted to fall freely, or piddle, into a can, may be backwound through an oven. A combination of techniques, in which the yarn passes over a beater bar, which removes the excess water,

and then through an oven, may be used. A yarn may be placed in a can so that air can be blown through the yarn,

for. instance, by use of a mesh screen bottom in which the air is fed via the can bottom through the yarn. Al-

In order to disclose more clearly the nature of the presscope of the invention nor limitthe ambit of the appended claims.

Example I This experiment demonstrates that uneven drying is the cause of regression.

Six carpets about eight inches wide by four feet long,

I identified as A, B, C,.D, E and F, were made from three Samples selected from the same batch of polypropylene yarn containing 3 parts per hundred of the resin (phr.)

of atactic.polyvinylpyridine which had been melt-spun and activated with sulfur dioxide, care being taken to obtain yarn which had all .been'made under the same process conditions. The yarn was usedas it came from the piddle can after activation and before drying, and contained about 35 to 50% OWF moisture.

carpet dyed 'to ada'rk color according to visual'exinina- 'tion.

Carpet B: The second sample of yarn was sealed in a polyethylene bag at 90 F. for,48 hours after activa- ..tion. The yarn was then removed from the polyethylene bag, and wound into a number of one pound packages. Some packages were retained to form carpet E below and the remainder immediately tufted into a carpet. The carpet was immediately dyed using a dye bath similar ,to that used with carpet A. The resulting carpet was lighter in color than. carpet A, about 20% lighter, by visual examination. 7 p Carpet C: The third sample of yarn was sealed in a polyethylene bagat 80--90 F. for 120 hours after activation. The yarn was then removed from the bag, and wound into a number of one pound packages. Some packages were retained to form carpet F below, and the remainder were immediately tufted into a carpet. The carpet was immediately dyed according to the procedure used for carpet A. Upon visual examination, carpet C was lighter in color than both carpets A and B, and contained some white spots where no dyeing was apparent.

Carpet D ,was made from the same yarns as carpet A, except that the packages were stored (or lagged).under ambient conditions (60-80% relative humidity at 80- F.) for 72 hours after winding. The packages were then tufted into a carpet and dyed according to the same procedure as used with carpet A. The resulting carpet was lighter than carpet A and showed a chevron effect indicating variation in dyeability of the yarn from the in- 'side portion to the outside portion of the package.

Carpet E was made from the same yarns as carpet B except that the packages were stored under ambient conditions for 72 hours after winding. The packages were then tufted to form a carpet and dyed according to the procedure of carpet A. Upon visual inspection, the carpet was about 60% lighter than carpet B and exhibited a chevron effect similar to that of carpet D.

Carpet F was made from the same packages as carpet C except that the packages were stored under ambient conditions for 72 hours after winding. The packages were then tufted into a carpet and dyed according to the procedure used for carpet A. Upon visual examination, th carpet F appeared to be the same as'carpet C. v

The results of the experimentation are summarized in Table 1 below.

The results of theexperiment may be interpreted as follows. First, activated polyolefin yarns which are subjected'to uniform storage and drying conditions hav'e'a uniform dyeability. Drying through exposure to an ambient atmosphere in the carpet form has been found to be equivalent to uniform drying where, as here the carpet is relatively small. Drying'occurred during and after the tufting of carpets A and B which required about two hours. As the limit of maximum regression is approached,

non-uniformity tendsto occur as is'shown by carpet C. 65'

Winding into large packages results in non-uniformity of drying. i I H w Second, the dyeability is maximum if the yarns are dried at ambient temperatures within about four hours after activation, as is carpet A. The dyeability decreases with time before drying reachinga minimum between 48 and hours as may be seen from the fact that carpet F is the same as carpet C, even though the yarn used to form carpet'F had been exposed to non-uniform drying conditions by being wound into and maintainedin package form after the tufting of carpet C.

Third, moist yarn that is otherwise uniformwhen wound 'onto packages loses its uniform susceptibility to. dyeing. This is apparently due to the non-uniform drying from the inside to the outside of the package.

Fourth, yarn that has reached a minimum dyeability slug by use of a pneumatic piston. The follower was again hand tightened against the cylinder and slug, retaining the material under the uniform 68 p.s.i.g. pressure, and the piston removed.

The cell was inserted into the'sample holder of a prior to packaging is not affected by nonuniform drying model D-1 Color-Eye colorimeter made by the Instruonthe package. ment Development Laboratories, Inc. The Color-Eye in- TABLE 1 Carpet Wound into package Tufted Lagged in Visual results A.-. Immediately after activa- Immediately after winding Dark, uniform, color.

1011. B 48 hours after activation ..do Polyethylene bags Light, uniform color;

. lighter than A. C 120 hours after activation do d0 Llghter than B; some white sp s. D Immediately after activa- 72 hours after winding Package. Lights; than A; chevron tion. e co E 48 hours after activation; do ..do 60% lighter than B; chevron e ec F 120 hours after activation do .do Same as carpet 0.

Example II strument consisted of a structure defining an optical path This example demonstrates that moisture content is the predominant feature causing regression.

An undyed carpet made from polypropylene containing 3 phr. atactic polyvinyl pyridine, melt-spun into yarn and activated with sulfurxdioxide and which was known to be uniform in dyeability from previous dyeing of samples of it, was cut into four lengths identified as samples 1, 2, 3, and 4. Sample 1 was the'control and was dyed in a 0.15% Anthraquinone Blue Sky, (CI. 62105) dye bath for forty-five minutes. The dyedcarpetwas adark blue color.

Sample 2 was soaked in Water at 75-80 F. for 60 hours, then dyed in the same manner as Sample 1.

, Sample 3 was pre-scoured with ammonium hydroxide and then soaked in water at ambient temperatures for 60 hours, and then dyed in the same manner as Sample 1.

Sample 4 was pre-scoured With hot water containing no ammonium hydroxide, and then dyed in the same manner as Sample 1.

All the samples of the carpet dyed uniformly. Carpe 1 dyed to the darkest color. Carpet 2 was lighter than carpets 1 and 4 but darker than carpet 3. Carpet 3 was lighter than any of the other carpets. Carpet 4 was lighter than carpet I but darker than carpets 2 and 3.

In order to express this relationship quantitatively, the reflectance of each of the samples was determined and is shown below in Table 2. The reflectance was determined by the following procedure.

Yarns were removed from each of the. samples and to shorter lengths about & to inch long, with some particles resembling powder. The ground sample was placed into a sample holder made up of 1) an externally threaded annulus of metal having an internal lip and being about "1 /2 inches in diameter, (2) an optically fiat, glass lens disposed inside the annulus'and retained by the lip, (3) a circular metal slug disposed in 'the'annulus and being about /2 inch thick and slightly smaller-than the internal diameter of the annulus and (4) a threaded follower adapted to engage the external threads on'the annulus and urge the metal slug towards the glass lens.

The ground sample was uniformly distributed between the glass and the metal slug. The amount of sample used was sufficient to provide at least a millimeter thickness in the holder, which is an infinite thickness as far as light I between a light source and a standard of known reflectance placed in a definite spaced relationship with a sample of unknown reflectance and in an opening at a particular position on the exterior of a small, about 6 inch, sphere. The light reflected from the standard and the light reflected from the sample were made alternately to fall on a photo-multiplier tube in rapid succession, and continuously during the measurement, by means of a flicker mechanism. An electronic system measured the percentage difference between the reflected light from the sample and standard. The colorimeter was calibrated to give a direct reading of the difference in percentage reflectance between the standard and the sample. Provision is made in the instrument for inserting into the optical path one of 19 filters of mutually different transrnission wave lengths. Sixteen of the filters pass narrow band wave lengths at 20 millimicron intervals from 400 to 700 millirnicrons. The other three filters are the wellknown X, Y and Z filters of known wave lengths, used in tristimulus systems.

Reflectance readings were taken with the X, Y and Z filters, and the filter corresponding to the predominant wave length of the sample, successively disposed in the optical path. The numerical readings were adjusted to CIE (International Committee on Illumination) values by a mathematical computation compensating for the known variables. The Y filter reading [Y(CIE)] corresponds to Munsclls Value, or C.I.E. Luminosity, or Hunter Lightness, and indicates the darkness or lightness of the sample without regard to color, that is, without regard to hue or chroma (Color-Eye Instruction Manual, 1963 Edition, p. 18). The reflectance values so obtained are relative to one another and are used herein only to compare competitively dyed samples, that is samples dyed simultaneously in one dye bath. Additional data may be required to obtain absolute values for comparing samples prepared at diflerent times and under different conditions.

It is desirable that the'darker samples are expressed by a larger number than the lighter samples. Therefore, the reflectance was calculated from the formula:

1000 Reflectance -?(cm water but without than 2 and 3.

Example III This example demonstrates the criticality of the time of and temperature at which the samples were exposed to water.

A polypropylene fiber containing 3% OWF of atactic polyvinyl pyridine was melt-spun, drawn and texturized by methods common to the art into a continuous yarn of 4000 denier having 156 filaments (4000/ 156 bulk). The yarn was activated with sulfur dioxide by placing the moist yarn in a sulfur dioxide atmosphere for a predetermined time. The yarn was dried and knitted into a 30 foot long tube about 6" in diameter.

The knitted tube was cut into twenty 9" segments. Each segment was then exposed to an aqueous environment for a series of particular times and particular temperatures. The environmental temperatures were 80 F., 125 F., 175 F., and 212 F. The aqueous environment consisted of one gallon stainless steel containers about three-quarters full of water and regulated within plus or minus 3 F. throughout the trial. Five samples were placed in each of the baths at the same time and samples were removed at predetermined intervals. The first sample was removed at the end of 1 minute. Successive samples were removed after 30 minutes, 1 hour, 2 hours, and 4 hours.

After the samples were removed from the aqueous bath, they were centrifuged immediately for about seconds to reduce the moisture level to less than 10% OWF water. The samples were then further dried for about fifteen minutes in a forced hot air oven at 240 F.

The dye bath contained 0.1% of Anthraquinone Blue Sky (C.I. No. 62105). Also, 0.15% Triton X-100 OWF and 3% formic acid OWF were added to the dye bath as is common in the art. The samples were maintained at a rolling boil for 45 minutes during dyeing.

The reflectance of each sample was determined as described in Example II, except that measurements were made on the knitted fabric without grinding. The samples were mounted on a board for display in the instrument. The results are shown below in Table 3.

The dried samples were pre-scoured in a dye bath with 1% OWF Triton X-100 and 3% OWF soda ash, then dyed in common and post-scoured for minutes at 160 F. in a solution similar to that used for the pre-scour.

The holding of the samples in a controlled moisture environment and drying quickly at the end of a predetermined period can be said to be equivalent to drying at a constant rate for the predetermined period and is susceptible to more delicate control than is an air drying method where control of air volume is required in order to achieve drying in a predetermined time. In any case, the critical point is that, to avoid regression, the moisture content of the yarn must be reduced to less than 3% CW within a required time for a given temperature.

The samples were also examined by skilled textile color experts and evaluated as to whether they were commercially acceptable in view of the effect of regression on their dyeability. The samples marked A in Table 3 below were determined to be within the preferred range of acceptability. However, it was recognized that those samples adjacent to the preferred ones may be acceptable for certain applications. It was clear that, the farther rev moved the sample was from the preferred range, the less acceptable it was. The information shown in Table 3 formed the basis for FIGURE 1.

TABLE 3 Water temperature Time of immersion (min.) F. F. F. 212 F.

' 32.92 A 37.97 A 33.77 A 32.29 A 30.35 24.62 32.01 A 28.80 22.76 30.48 26.54 19.98 29.31 24.41 18.86

Example IV This example demonstrates the criticality of final moisture content.

Yarn was prepared as in Example III and knitted into a six inch tube. The knitted fabric was cut into six samples about six inches long.

The samples were then impregnated with water to 0, 2, 3, 4, 6 and 10% OWF. The samples were stored individually in airtight plastic containers for 68 hours and then dyed in a common dye bath with Anthraquinone Blue Sky (C.I. No. 62105) as in Example III. Reflectance measurements were made as in Example III. The results are shown below in Table 4.

The samples were also evaluated by textile color experts. It was determined that the samples containing 3% OWF or less of water regressed little or not at all. Those containing 4% OWF or more water regressed to a greater extent.

Based on the evaluation, it was determined to be critical to dry yarn to 3% OWF or less moisture content, preferably to 0.62% OWF TABLE 4 Water content percent OWF: Reflectance 0 45.43 2 45.48 3 44.74 4 41.55

The terms and expressions which have been employed are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof, but it is. recognized that various modifications are possible Within the scope of the invention claimed.

Having thus described our invention, what we claim and desire to protect by Letters Patent is:

1. A method for rendering yarn comprising a blend of a polyolefin and between about 0.5% and 10% .of a basic polymer dye receptor uniformly dyeable with anionic dyes, which method comprises: activating said yarn by contacting it with a Lewis acid or Lewis acid generating material of sufficient concentration to reaction with said basic polymer dye receptor contained therein to form a reaction product, and then drying said yarn at a temperature and within a time after activation shown at or below curve A in FIG. 1 to a moisture content below about 3% on the weight of the fiber.

2. The method as defined in claim 1 in which the Lewis acid is sulfur dioxide.

' 3. The method as defined in claim 2 wherein the yarns are dried to a moisture content between about 0.6% and 2% on the weight of the fiber.

4. A method as defined in claim 2 wherein the drying References Cited itgguisfocgrrrligdlrgut at ambient temperature in less than UNITED STATES PATENTS 5. A method as defined in claim 2 wherein the time re- 3,361,843 1/ 96 Mi ler 615 a1. 260875 quired for drying is not substantially greater than about one minute 0 DONALD LEVY, Primary Examiner 6. A method as defined in claim 2 wherein the drying I step is carried out at about 125 F. or below in about 60 us C minutes or less. $100 115.5 168; 3430; 260897 

